Lubricant



y 1950 R. WAITKINS 2,506,049

LUBRICANT Filed Dec. 18, 1946 o Represenfs 24 Hour Test 50 A Represents 48 Hour Test I u Represems 72 Hour Test Ml. Sludge /|O Ml. Of Oil O 0.5 IO .l5 .20 v25 0 Se As Tribufyselenonophosphufe In Pennsylvania IOW Bose Oil INVENTOR George R. Woitkins Attorney Patented May 2, 1950 lTD 2,506,049 LUBRICANT George R. Waitkins, Flemington, N. J., assignor to Battelle Memorial Institute, Columbus, Ohio, a

corporation of Ohio 13 Claims. 1

This invention relates to improved lubricants and, more particularly, to lubricants comprising a. lubricating oil and a minor amount of a, selenonophosphate.

When high-purity oils were introduced as lubricating oils, immersion oils, transformer oils, extreme pressure oils, and the like, they brought with them the problem of oil deterioration. These oils may deteriorate either by decomposition of the oil molecule, or by polymerization. A number of tests have been devised for measuring or indicating the exact degree to which any particular oil has deteriorated under given test conditions. For example, the presence of sludge is an indication of the formation of intermediate products through break-down of the oil molecule, whereas the acid number measures the extent to which the oil has been oxidized to produce free acids. An increase in viscosity indicates polymerization of the oil, and the carbon-content increase is a further measurement of the degree of decomposition of the oil. The formation of varnish upon surfaces which are oiled or subjected to the treatment of oil under high temperature or pressure indicates the tendency of the particular oil to form extremely hard polymers or resins upon metal surfaces which are being continuously exposed to the oil.

Oil is quite a complex mixture of compounds and one oil may frequently differ greatly from another, especially as to the particular manner in which it deteriorates or breaks down; that is, one oil may under test conditions produce a great deal of sludge with very little, if any, bearing loss, Whereas another oil under identical test conditions will produce very little sludge but will show a high bearing loss. Consequently, it has been the practice in the art to produce additives having the general property of inhibiting oxidation or deterioration of the particular oil in question and which, .as a special attribute, are designed to be especially effective in preventing sludge formation, increase in viscosity, high carbon residue, or some other particularly desirable property.

It is an object of this invention, therefore, to provide an improved lubricant consisting essentially of a lubricating oil and a minor amount of an oil additive for inhibiting the oxidation of oils.

Another object of this invention is to provide a lubricant containing as an addition to the lubricating oil a minor amount of an oil additive which markedly decreases the sludging of oils subject to metallic catalysts, heat, etc.

Still another object of the present invention is to provide a lubricant containing a minor amount of an oil additive especially characterized by the property of reducing, and in some cases eliminating, lacquer formation on surfaces constantly exposed to the oil.

A further object of the present invention is to provide a lubricant containing as an addition to the lubricating oil a minor amount of an oil additive especially designed to so inhibit lubricating oils that engines employing the same will remain clean and be relatively free from carbon, lacquer, and other foreign matter.

Other objects and advantages of the present invention will become apparent to those skilled in the art from the following detailed description thereof when read in conjunction with the accompanying drawing in which the single figure is a graph illustrating the sludge-forming properties of a lubricant comprising the present invention.

In general, the present invention comprises a lubricant consisting essentially of a lubricating oil and a minor amount of an additive containing as an essential ingredient thereof an oil-insoluble organic selenonophosphate.

It has been found that oil-soluble organic selenonophosphates provide highly effective oil additives and are especially suitable as lubricating oil additives. These compounds have a general formula Where R1, R2, and R3 are aryl, alkyl, alkaryl, or aralkyl groups, and X may be hydrogen, a halogen, or the like. Usually, these groups are the same in any one compound as, for example, in tributyl selenonophosphate and triphenyl selenonophosphate, although they may all differ from one another.

The selenonophosphates may be readily prepared by adding the theoretical amount of selenium to the corresponding phosphite. Since this reaction is highly exothermic, it is desirable to place the phosphite container in an ice bath until the selenium has had an opportunity to dissolve. Following dissolution of the selenium, the ice bath may be removed and the solution stirred and filtel-ed to remove any undissolved selenium. The temperature of the solution will, of course, rise until the dissolution ofthe selenium is complete. In order to insure complete dissolution of all selenium and reactance with the phosphite, the preferred procedure is to heat the solution from :at least 5 to about 30 minutes at approximately C. There are no particularly critical features in the preparation of the selenonophos- 3-ethy1 hexyl) di-subi-n-butyl), low-carbon or shorta mixture of alkyl and aryl groups (diphenyl butyl), and aryl (tricresyl). Other types 0.

1" selenonophosphate V esters not or high-carbon alkyl (tri stituted aiiiyi chain ai yl (tri-butyl),

above setiorth may, of ,course, be employed.

phates, although heating for prolonged periods of time will produce a gummy, polymerized mass rather than the desired product. Among the compounds which have been successfully me pared in this manner are triamylselenonophosphate, triisoamylselenonophosphate,: tri-3 etn'yl TABLE 1 Indiana stirring oxidation tests on selenonophosphates Averagevaines'ofioil Deterioration Properties Percent Viscosity Increase Acid No. Increase Sludge Additive Triamyl-selenonophosphat... Triiso'amyiselenonophosphat I." 'Tri-3-ethy1 .hexyl selenonophosphate Di-n-butyi chloroseienonophosphate. f 'Tributyl seienonophosphate. iDiphenyl butyl' selenonophosphate .I'gricresyl selenonophosphatm one"- *Not 'suflicient sam'pie remaining for test.

The amount .oiE-additive added to ithe oilthas been found not-towbe highlycritical;however, ,:the1'e are certain preferredt-ranges *Whichevary ii-hex yl 'se1enonophosphate,.. di-n-butyl chlorose1ereated aandathe particular 'rSincel'these ieadditivesiihave 1 c. fferent molecular; weights andzcontain different percentages i of 'the active ingredient, selenium,

phate, and tricresyl.:selenonophosphate. These compoundslin amountsequal-to 0.15 percent seeniumiiniithe' lubricant were; added to;.a -standardrlubric'ating oil iandtestedin an :Indiana I stirflfhe;fdata:"are recorded.:in ithe .followirv a the per centby-weight "ofs'elenium da thefirial Table. 1.

iollow' g Table test results are showntwhich Wereobtained through the'examinationfof an exmageformed :in 621011 10minfliteI'STOflOfl during the test-period. flt is at onceappar entithat alifof 40 -"'th'e lubricants "containing the selenonophosphate "'"a'dditi'ves 'Were' mu'ch superiorto the same; lubri- ..emp1ary 1 .selenono.phosphate,.j tributyl "selenonophosphate, addecito. ausual typeihaseloihnamely, Pennsylvania ,SAEAO. llhese testswereall run cant Without-these additives. A "comparison of the tria-myl andthe"triisoamylselenonphosphates in accordance with procedure knownras 'indicates that .brari'ch'ed Chain-9517911: groups 'may diana stirringqoxidationqteststdescribedinlndusfn'creaseconsiderably the 'frectiveness "of; the-adi rial. E n r n -i Ch mifitryreanalytical edition, ditive. volume 13, page 317.

TABLE 2 findiana stirring oznz'dation tests ontrihutyl vselen onophqszzhjate;.iWRennsylvania I 72 Hours 561 1 lo lloonvn w unu NMLLL 9 07 8 F A r aii an ntma tsa i .24 Hours 5 5 7410 0 -bo ofino 6533 55 a i T.

Initial V 000000LL00 7917 .H 00000 LL00 000000000 V i 11 t 7 17 121 1 84 000000000 Per Cent Selenium 0 0 O O Q000 fl .0 0 0 00 0 0 0 0 0 0 -Test Arbitrary assignmentiofzrumbers between 1 and 10 ingwhich 10,-.designates fltper,feet1y-:c1ean-.rodandl a V yer-y .dirty .rod. 1 7 V The compounds: shown in t-Tabie 1- .wrepresent "'widelyvariant :ty-pes of 'organic selenonophos- V The data above, setiorth inTable 2 in connection With sludge, formation are graphically. illustratedr inlthe accompanyinggfigure, wherein the :yl);-branch-chain: a1kyi (triisoamylx, longechain .percent of-seleniuniinQthehil( intheiormbf triphate esters such as straight-chain: alkyl. (triamaccepts "butyl selenonophosphate) is plotted against the milliliters of sludge formed per 10 milliliters of oil. It is at once evident that even minute quantities of selenium, as little as 0.01 per cent, effect a re- 6 Speed ...1600 R. P. M. Load .1.50 H. P. by two-blade fan Jacket temperature 345 1 5 F. Oil sump temperature 225 5 F.

mal'kable reduction in the amount of Sludge 5 Prior to the start of the test, a break-in run was P The sl'eatestljeductwe of Sludge q made at 1200 R. P. M. for 30 minutes. Every 30 Powever, 1 n Wlth thls partlculal hours the engine was removed from its base and addmve and Partlcular 011 m a g of 29 1 inspected and the crankpin bearings weighed. about totabout 2 2 1 dd 3 m The engine was then re-assembled and the test P i t i g a f ,z g continued to 240 hours, at the end of which time 13 hpnman g y t e SE: i gg the used oil was analyzed for Conradson carbon oug grea er n p residue and naphtha insolubles expressed in per um had little, if any, added effect and in certain Cent by weight cases were somewhat less effective than smaller 15 The demerit system shown in the above Table amounts- Although the data m Table 2 and the 3 is urel an em irical method of establishin single figure refer to tributyl selenonophosphate, p y p g it has ben found that the concentrations of sethe extent to which the Vanous parts of the motor lenium at which this additive may best be used is exposed to the on have been afiectefi by lacquer typical of the other oil-soluble organic selenonoas as the extent to which 011 has broken phosphate down to produce sludge. It is evident, however,

The effect of concentration variation of the sefrom these, tests that Selenonuphosphate lenium in the additive with respect to acid num- P F to any the other ber, varnish formation, and viscosity increase, as five confmferclal m addltlYes tested shown in Table 2, indicates a marked improveunder similar conditions. Still more impressive ment in the properties of the oil when the seleniare the tefsts Showing the deposition of lacquer um is present in percentages varying from as liton the Sklrt and 'cyllnder head- In Yhese tWQ tie as 001 to 0.25 per cent The Smaller concem areas, the test engines were substantially free trations seem to be very effective in reducing the m any deposit whatsoever, and the area covacid number, and further additions show very fired by the Sklrt lacquer Was y One-fourth little improvement over the results achieved by as h as e area v r y h n cleanest adding 0.05 per cent selenium in the form of triadd v The pr p ta n num er, an indicabutyl selenonophosphate. The decrease in vartion of sludge formation, was less than one-half nish formation, on the other hand, reaches a of the next lowest additive. The formation of maximum at about 0.15 per cent selenium. The carbon in the oil to which tributyl selenonolowest percentage increase in viscosity over a phosphate had been added appeared to be about period of 48 hours was obtained with tributyl seaverage in comparison with all of the other addileno phosphate add t ve Containing 0- pe tives tested, but a total of 0.56 gram of both cent selenium in the final oil. naphtha insolubles and carbon disulphide in- Oil-soluble selenoncphosphates comprising the solubles were present in the sludge from the test present invention have been found to be especialoil to which tributyl selenonophosphate had been 1y desirable where cleanliness of the parts coming added as compared with the next lowest figure of in contact with the oil was an essential feature 1.10 grams for additive B. It can be said from a and where minimum sludging of the oil was also perusal of Table 3 that the tributyl selenonophosrequisite. Comparison of tributyl selenonophosphate additive, as representative of the organic phate with other commercial additives shown in selenonophosphates generally, is apparently suthe following Table 3 discloses that the selenonoperior to the other commercial additives as rephosphate additive is greatly superior as respects spects its property of maintaining surfaces exits property to prevent lacquer formation and posed to the oil free from deposits. sludge formation. The data in the following Although the above tests refer particuarly to Table 3 has been compiled using tributyl selenolubricating oils, the use of the additives comnophosphate at 0.1 per cent selenium concenprising the present invention is not limited to TABLE 3 Lauson engine tests [Demerits at 250 hours.)

Tributyl Commercial Additives Selenonophosphate A B G D E Skirt Lacquer 045 0. 5 2 2 1 2 z Sludging 0-10) 0 2 2 0 2 0 Total Demerits 0. 6 4 4 1 4 2 Observed and Measured Deposits:

Skirt Lacquer Area 5.0 50 30 20 30 30 Skirt Lacquer Thic1mess "Ins" 0 .0005 .0000 0 .0002 .0001

Cylinder Head Deposits Gms 1) 8.0 6.25 9.0 11.25 11.5 Oil Consumption, Lbs./Hr.: Av. for 250 Hours .0028 .0165 .003 .003 .005 .006 Residue Tests: v

.Preclpitation No -per cent.. 0.75 3.0 4.0 3.0 2.0 5.0

Original Conradson Carbon Residue "10..-. 0.39 0.23 0.46 0.51 0.56 0.38

Oonradson Carbon Residue, Final do. 3. 88 1. 39 4.8 4. 96 2. 0 3. 88

Naphtha Insolubles do 040 0. 0a 2.6 2.36 0.12 1.82

Carbon Disulphide Solubles do 016 0.34 1.3 0. 0.38 0.64 Piston Rating: 1 (Oleanest) to 5. 1 1+ 2 2- 2 1+ tration in an SAE No. 20 lubricating oil. The oils were tested in Lauson single-cylinder engines using the high piston temperature procedure under the following operating conditions:

such oils but may be extended to electrical immersion oils, transformer oils, and the like. The following Table 4 discloses Indiana stirring oxidation tests run on electrical immersion oils. The

k prising a major minor amount against oxidation-L of an- -oil soluble compound selected from' they-group :consisting of alkyl, alkaryl; a rallryl; and-aryl selenonophosphates.

low acid number obtained by adding .tributyl .-.-selenonophosphate to the electrical immersion :oil

tested is an indicationiof decrease in-* corrosive properties of theoil, whereas the low-percentage ...of increase .in.viscosity. obtained by addingthis additive shows. a decrease-in" the polymerization of the .011. Both of these factors are highly important, especially'in' large electricalinstallations Where large. quantities of'joilare to be 'used over long periods of time.

The selenonophosphate additives "may be used "alone or in combination with'other additives. For ""example, amixture of 'tributyl selenonophosphate (0.10 per cent Se) and a percent solution of ""selenium-dioxide (0.05 per cent Se) in 'b'enzylalcohol proved-to be particularlyeffective in reducing bearing corrosion.

" It is apparent from the'above' detailed description' thereof that the present invention comprises an improved lubricant-consisting essentially "of a lubricating oil and I an 1 oil-soluble 1 organic "selenonophosphate ester. By '-adding -these esters, e'itheralone or in combination with such additives 'as seleniumdioxide, oils may be produced which aresuperior to those nowtin use in that they show i less sludgeformationrand' increased motor clean- 'liness.

TABLE 4 r cientl to -stabilize: the oil. .against oxldationwoiz a remixture of an oil-soluble compound' selecte'd from :the group consistingofalkyl,.alkaryl, aralkyl and l aryl I selenonophosphatea andwselenium-dioxide.

9. Alubricant consisting essentially oi anhydrocarbon lubricating oil and: an oil-soluble com- .pound: selected -fromthe. group consisting of alkyl, alkaryl, aralkyl, and: aryl =selenonophosphates in a concentrationsuch .that the result- King lubricant contains from at least 0.01 "to about.0.25-% byweight of selenium.

10. A :lubricant :consisting essentially f; a.

1 hydrocarbon lubricatingoiland Man oil -soluble -=compound :selectedfrom thengroup consisting-Lot alkyl, alkaryl', ara'lkyl and-- aryl .selenonophosphates,"inaconcentration suchthat theresulting lubricant contains from 1 0:10 -'to 0-.15 by weight oflselenium.

i 11. A clubricant consisting -essentiallyof a hydrocarbon lubricating oil and: atmixturesof-an oil-soluble i'com-pound selected. from -thewro'up consisting of- -alkyl,-- :alkaryl; aralkyl, 1 aryl selenonophosphates in concentration suchlthat the resulting lubricant-contains; about 010% by Weightrof selenium -:assaid selenonophosphate, and: about 0-.05%--by weight of selenium 3.82581811- ium dioxide dissolved in anorganic alcohol.

vIndiana stirrmgaoxidation tests over. a period of -24h0u1's rumomelectrical immersion oils.

Sludge ml.= Acid No.mg. -Viscositv PerCent Additive per 10 ml. KOH per Increase, selenium ...or oil mu PrCent "Tributyl selenonophosphata. I .0. l0 0 7. 28 "573 J 130.-.-.. J 0.15 n 0 0.27 128 None 8. 0 32. 01 Solid 'What is claimed is:

- 1. An improved: 11211161312011 composition cornznount-ofa mineraloil and a afloient .tostabilize the oil 2. Y A' lubricant' comprising a: major amount of a mineral lubricating-oil and a-minor amount of sufficientto stabilize the. -oil-against oxidation of diphenyl butyl: selenonophosphate.

i 3. A lubricant com-prising a .major amount of a mineral lubricating oil and a minor amount suflicient to stabilize the oil against oxidation of tributyl selenonophosphate.

4. A lubricant comprising a major amount of a mineral lubricating. oil and .from about 0310 to about 0.15 per cent by weight of selenium as diphenyl butyl selenonophosphate. g

5. A lubricant comprising asmajor amount of a mineral lubricating oil :and from l about 0.10 to. about 0.15 per centrby weight of selenium as.

tributyl selenonophosphate.

6. A lubricant comprising a major amount of a mineral lubricating oil, about? 0.101 per cent by weight of selenium as tributyl s'elenonophosphate and about 0.05 per cent by weight 'of'seleniumxas selenium dioxide in benzyl alcohol.

'7. A lubricant consistingessentiallyof a hydrocarbon lubricating oil and aiminor amount-sunlcient to stabilize the'ioil against oxidation of an iv12.-.A lubricant consisting essentially 0f v a hydrocarbon lubricating oil and aminor' amount :suficient to stabilize theoil against oxidation of :an oil-soluble" :organic compound of @theutype "in which R1 and R'z representalkylaar l; alka'z iyl,

r or a'ralkyl groups and X- representshydro'gen or a -halogen atom. r

13. An improved mineral "oil composition com prising' -al major amount of a mineral oil and a 2:.minoramountrs1i-ificient to stabilize the oil against oil-soluble compound selected from the group rconsisting 01L alkyl alkaryl, aralkyl and aryl I selenonophosphates.

- 8. A :lubricantconsistingessentially of a hydro- -..-.carbon. lubricating oil and a minoraznount suffi- Number Name Date 215K452 "Hurriphreys fMayf 91 1939 2,355,106 Prutton Aug? 8,1944 Y 2,359,270 Sh utt et a1 ".Sep t. 26, 1 944' 2,359Q331 vRLiif c... Oct; 3', 1944: 

1. AN IMPROVED MINERAL OIL COMPOSITION COMPRISING A MAJOR AMOUNT OF A MINERAL OIL AND A MINOR AMOUNT SUFFICIENT TO STABILIZE THE OIL AGAINST OXIDATION OF AN OIL-SOLUBLE COMPOUND SELECTED FROM THE GROUP CONSISTING OF ALKYL, ALKARYL, ARALKYL, AND ARYL SELENONOPHOSPHATES. 